Hydrocarbons, such as oil and gas, may be recovered from various types of subsurface geological formations. Such formations typically consist of a porous layer, such as limestone and sands, overlaid by a nonporous layer. Hydrocarbons cannot rise through the nonporous layer, and thus, the porous layer forms a reservoir in which hydrocarbons are able to collect. A well is drilled through the earth until the hydrocarbon bearing formation is reached. Hydrocarbons then are able to flow from the porous formation into the well.
In conventional drilling processes, a drill bit is attached to a series of pipe sections referred to as the drill string. The drill string is rotated and, as the drilling progresses, it is extended by adding more pipe sections. Larger diameter pipes, or casings, also are placed and cemented in the well to prevent the sides of the well from caving in. Once an appropriate depth has been reached, the casing is perforated at the level of the oil bearing formation.
If necessary, various completion processes then are performed to enhance the ultimate flow of oil from the formation. The drill string is withdrawn and replaced with a production string. Valves and other production equipment are connected to the well so that the hydrocarbons may flow in a controlled manner from the formation, into the cased well bore, and through the production string up to the surface for storage or transport. Once a well has been producing for a period of time it may become necessary to “workover” the well, that is, to repair or replace various well components or to stimulate the formation.
The rigs and equipment used to perform those operations are similar in many respects. Drilling and workover rigs both have a derrick or mast which supports a drill floor. The drill floor is elevated above ground level to accommodate various well components, such as blow out preventers, valves, and the like. A traveling block is suspended from a stationary block on the derrick crown. The traveling block is used to handle sections of pipe so that they may be added or removed from a string by workers on the rig floor.
The process of inserting and removing joints of pipe is referred to a “tripping” in and out of the well. Reducing the number of trips is a constant goal, but nevertheless many well operations require tripping in and out of the well several times. At best a well is hundreds, but more typically is several thousand feet deep. Thus, well operations necessarily entail transporting many joints of tubular members, such as drill pipe, casing, and production tubing, from a storage rack to rig floor or vice versa.
Each joint of pipe is heavy, and the rig floor also may be as much as 20 to 30 feet above ground level. Thus, various devices and systems have been developed to assist in transporting pipe between a rack and the rig floor all with a view toward increasing efficiency, minimizing handling of pipe by rig workers, and reducing risk of injury to those workers.
For example, U.S. Pat. Nos. 6,533,519, 6,719,515, and 6,969,223 to K. Tolman et al. disclose a pipe handler which has achieved considerable commercial success. Pipe is fed to a rig floor by manually rolling joints of pipe off a rack, onto the pipe handler's main platform, and into a groove in the platform. The forward end of the pipe then is elevated and moved toward the rig floor by a pusher, which pushes the rear end of the pipe laterally through the groove, and a carriage, which supports the forward end of the pipe in its elevated position. Workers on the rig then are able to use equipment on the rig to grab the pipe and move it into position for insertion into or “making up” a string. The process is then essentially reversed as the string is broken down on the rig and pipe is transported by the handler back to the rack.
It will be appreciated, however, that the particular handler illustrated in the Tolman patents is skid mounted and designed to be carried on a trailer. It also requires that pipe be rolled manually on and off the platform to and from a separate pipe rack that is essentially at the same level as the platform. Thus, the design of those handlers has been improved by building them into a trailer and by providing components designed to roll pipe into and out of the groove. Other improvements include providing area on the trailer for loading a multi-level rack of pipe and elevators for transporting pipe to and from the rack levels.
Despite the success of such designs, however, there is a continuing need to further minimize physical handling of pipe and to increase the efficiency and safety of pipe handling operations. Likewise, there is a continuing need to improve the reliability, simplicity, and serviceability of pipe handlers and thereby to reduce their costs of construction, operation, and maintenance. Such disadvantages and others inherent in the prior art are addressed by the subject invention and its various embodiments, which now will be described in the following detailed description and the appended drawings.